Electric plug construction



Feb.19, 1935. A. E. GRANT 1,991,849

ELECTRIC PLUG CONSTRUCTION Filed-June 8, 1952 2 Sheets-Sheet. 1

INVENTOR BY (Y SZ A ORNEYS Feb. 19, 1935. A. E. GRANT ELECTRIC PLUG CONSTRUCTION Filed June 8, 1932 2 Sheets-Sheet 2 INVENTOR Alhs'n E GranZ A ORNEYS Cir Patented Feb. 19, 1935 UNITED STATES PATENT OFFICE ELECTRIC PLUG ooNsrRUc'rIoN Albert E. "Grant, New York, N. Y. ApplicationJune s, 1932, Serial No. 615,979

' Claims. ((1200-51) My invention relates to electric plug constructions and one object of my invention-is to provide an improved switchplug of simple construction, the several partsof which may be cheaply made and easily assembled. a

Another object is to provide an attachment plug having improved spring sockets therein adapted to receive and-firmly grip the prongs of a leg plug or the prong-like attachment terminals of devices such as sad irons.

A further object is to provide an improved electric switch ofthe character popularly useful in attachment plugs, lamp sockets, etc. 7

Referring to the drawings forming a part of this specification which are on an enlarged scale and in which like reference characters indicate like parts in all views: 7

Figure 1 is a front elevation of an end plug embodying my invention and Figure 2 is a side elevation thereof.

Figure 3 is a plan view.

Figure 4, is an inverted plan view.

Figure 5 is a view of the plug as shown in Figure l with one half portion of the casing removed to reveal the assembled parts and shows the switch contacting or closed position.

Figure '6 is an interior view of one of the half portions of the casing.

Figure 7 is a view similar to Figure 5 showing the position of the assembled parts when the switch is open and the circuit thru the plug is broken.

Figure 8 is a sectional view ii-13 of Figure '7. r r a I a Figure 9 is a sectional view taken on lines 9--9 of Figure 7. I

Figure '10 is a perspective view of the switch mechanism assembled as a unit and ready for insertion into the casing.

Figure 11 is a perspective view of one of the strip conductors of the plug having a terminal nut formed integral thereon to receive one of the wire-binding screws.

The plug casing 15 is made in two like half portions of moulded insulating material, such as hard rubber. Each'half portion is recessed, as shown in Figure 5, so that when they are held together in assembled position by the screws 16-16, suitable passages, chambers, partitions and abutments are formed in the walls of the casing to properly receive and support the several parts assembled therein unattached to the casing. V

Extending inwardly from the top of the casing in communication with the chamber 21 is a centaken on lines tral circular passage 1'? to admit a cable 18 containing current supply wires 19l9. An annular groove 20 in the wall of the passage '17 serves to receive the wire ring customarily employed for clamping the insulating material of the cable 18.

On each side of the plug adjacent the lower end of passage 1'7, binding screws 22-22 serve to fasten the inner ends of wires 19 to hexagonal nut-like terminals 23- 23 removably seated in pockets of similar outline moulded in the casing wall. The terminals 23 are formed integral with resilient stripconductors 24 and 25 respectively, which extend downwardly along the inner side walls of the casing on opposite sides of the plug. The strip 25 is substantially shorter than the strip 24 and is bent inwardly adjacent its free end, as shown in Figure 7. Spaced apart from the strip 25 on the same side of the plug is the free upper end of a metal strip conductor 26 which is also bent inwardly. As shown in the drawings, the free ends of the spaced resilient strips 25 and 26 overextend each other and are inwardly bent and flared apart in such manner as to provide symmetrical and opposed resilient "contacts adapted to be depressed and bridged by a switch element 43 to obtain a spring pressed engagement therewith.

The lower end of the conductor 24 is angularly bent and perforated for permanent attachment intermediate the upper ends of resilient conducting socket members 27 and 28 by means of a rivet 29 drifted integral with member 2'7, as shown in Figure 9. In the socket chamber, below the rivet, these socket members are bent away from each other and looped back so that they face in abutment for a considerable distance to provide a springclip capable of receiving and firmly gripping a coupling prong inserted between them thru one of the apertures 30- in the base of the casing. When such a prong is inserted between them, the members 2.7 and 28 are forced apart against the spring resistance inherent in the material of whichthey are'formed so that they will grip prongs of various shapes and diameters over a large area, thusinsuring good electrical contact and firm mechanical connection.

The lower end of the conductor 26 is formed similar to the conductor 24 and permanently attached to a like pair of socket members in a chamber formed on the opposie side of partition wall 31.

A pocket 32, shaped as shown, is recessed in the half portions of the casing to contain a U- shaped. switch frame 33 which has slots 34-34 resilient conductors and 26.

ner. conductors, the element 43 is caused to wipe aligned laterally in its upwardly extending sides. Between the sides of the frame 33 is a switch member 35, the lower portion of which is reduced in width to provide shoulders 36-36 and the lower end of which extends thru a hole in the base of the frame. A compression sprmg 3'7 surrounds the reduced lower portion of the member 35 and extends between abutments aflorded by the base of the frame 33 and the shoulders 36 to support the member 35 and press it upwardly against a symmetrical double cam 40. This cam is formed on the lower edge of sliding actuator 39 which extends thru a slot 38 in the member 35 and thru the slots 34 in the frame. The top edge of the actuator 39 is cut away intermediate its ends to form shoulders 4l-=l adapted to alternately abut the opposie sides of the frame 33 and thus limit its sliding movements.

The ends of the actuator are rounded and extend externally of the casing thru suitable openings in its opposite sides so that the actuator may be manually operated. Adjacent its ends the actuator is marked off and on respectively, to indicate the condition of the switch.

An insulated arm 42 is fixed by one end at right angles on the upper end of the member 35 and a channel shaped contact element 43 is riveted over the other end of the insulated arm in position to bridge the bent free ends of the resilient strip conductors 25 and 26.

As shown in Figure '7, the circuit thru the plug is open. To close it, actuator 39 carrying cam is slid laterally by pressing in its projecting end marked OK. This movement of the cam forces member 35 downwardly against the resistance of spring 37 until the apex of the cam has passed thru the slot 38, whereupon the compressed spring'37 instantly operates to thrust member 35 angularly upward against the opposite inclination of the cam into the closed position shown in Figure 5.

In plunging angularly upward in this manner, element 43 is caused'to wipingly slide into bridging contact with the inwardly bent ends of the This wiping action keeps the several contacting surfaces clean and prevents arcing. The contacting pressure normally allorded by spring 37 is suflicient to compress the conductor ends slightly so that firm spring pressed contact is assured.

To reopen the switch, the end of the actuator marked on is pressed in to repeat the foregoing movements in a substantially reverse man- In breaking contact with the ends of the downwardly. against them before it is suddently thrust upward into the open position.

Having thus described my invention, I claim as new:

1. An attachment plug comprising a casing, a strip conductor of resilient metal supported within the casing and having a. free end transversely flared toward the central median line therethru, a second resilient metal conductor supported withinthe casing having a free end transversely flared toward the central median line therethru, the flared free end of said second conductor being opposed, spaced apart and overextending the flared free end of said first conductor to provide symmetrical and opposed resilient contacts, a switch mechanism carried in said casing having a contact element adapted to bridge the free ends of said conductors and to depress them against the yielding resistance inherent in thematerial of which they are formed to obtain spring pressed engagement therewith.

2. An attachment plug comprising an insulated casing formed in two parts and having a central passage extending inwardly at its top, resilient metal conductors carried within said casing on opposite sides thereof, wire binding terminals carried by said conductors adjacent the inner end of said passage, said casing having chambers formed therein adjacent its base, a spring socket carried in each of said chambers, one of which is connected to one of said conductors, the other said conductor having a free end bent toward the central median line thru the casing, a third resilient metal conductor supported in the casing having a free end bent toward the centralmedian line therethru and opposed, spaced apart and oxerextending the bent free end of said other free-ended conductor and attached at its opposite end to the other spring socket; each of said sockets comprising two strips of resilient conducting metal held together at their conductor-connected ends, bent apart and looped back in facing abutment with each other to provide a spring clip, said casing having openings in its base positioned to admit attachment terminals receivable in said sockets; a switch mechanism carried in said casing comprising a switch member, a spring supporting said member adja-. cent one end thereof, a contact element carried by said member adjacent its other end, an actuator supported for endwisesliding movements transversely of said member and having its-opposite ends extending externally of the casing thru openings in its walls, a double cam carried by the actuator in engagement with said member and adapted to first depress the member against the yielding resistance of said spring and then to guide the member angularly under the'reciprocal pressure of the spring; said contact element being positioned and adapted to bridge the bent free ends of said conductors and to depress them against the yielding resistance inherent in the material of which they are formed.

3. An electric switch comprising flat resilient conductors spaced apart and each having a free end overextending the other, said ends being in-, wardly bent and flared apart to provide symmetrical and opposed resilient contacts, and a switch member adapted to depress and bridge said contacts to obtain spring pressed engagement therewith. a

4. An attachment plug comprising an insulated casing having a central passage extending inwardly at its top, metal conductors carried within said casing, wire binding terminals carried'by said conductors adjacent the inner end of said passage, contact terminals carried by the casing adjacent its base, one of which is connected to one of said conductors, the other saidconductor comprising a flat strip of resilient conducting metal having a. free end flared toward the central median line thru the casing, a third flat strip conductor of resilient metal having a free end flared toward the centralrmedian line thru the casing and connected at its opposite end to the other contact terminal, said flared free ends being opposed, spaced apart and overextending each other to provide symmetrical and opposed resilient contacts, and a switch mechanism carried in said casing having a member adapted to depress and bridge said contacts to obtain spring pressedengagement therewith.

5. An attachment plug comprising an insulated casing formed in two complementary portions and having a passage extending inwardly at one end thereof, the interior walls of said casing portions being recessed to receive and position the several internal parts of the plug in freely removable relation therefrom, said parts comprising: wire binding terminals positioned adjacent the inner end of said passage, contacts carried by the easing at its opposite end, a conductor extending from one of said terminals to one of said contacts, and a manually operable switch mechanism adapted to complete a circuit between the other terminal and the other contact; and means for securing the casing portions together whereby the several internal parts are held assembled in 5 operative relation.

ALBERT E. GRANT. 

